Field assessment of avocado rootstock selections for resistance to Phytophthora root rot.

Phytophthora root rot (PRR), caused by P. cinnamomi, is a primary constraint on avocado productivity in Australia. Numerous field trials at sites in northern NSW and southern QLD have demonstrated significant variation in tree health amongst commercial rootstocks and recently selected material, grown under high PRR disease pressure. Selections 'SHSR-02', 'SHSR-04', ungrafted 'Hass' (rooted cuttings from clonal propagation) and the commercial rootstock 'DusaTM' were significantly healthier over time than other rootstocks, many of which died during the course of the trials. 'Reed' was consistently highly susceptible. In many cases superior tree health was associated with increased tree height and trunk girth. The trials also clearly demonstrate the negative impact of Phytophthora root rot on establishment of new avocado production blocks, and the importance of identifying and selecting avocado rootstock material that can withstand high P. cinnamomi disease pressure.

Population genetic evidence for the east–west division of the narrow-barred Spanish mackerel (Scomberomorus commerson, Perciformes: Teleostei) along Wallace’s Line

Mitochondrial DNA D-loop (control) region (426-bp) was used to infer the genetic structure of Spanish mackerel (Scomberomorus commerson) from populations in Southeast Asia (Brunei, East and West Malaysia, Philippines, Thailand, Singapore, and China) and northern Australia (including western Timor). An east–west division along Wallace’s Line was strongly supported by a significant AMOVA, with 43% of the total sequence variation partitioned among groups of populations. Phylogenetic and network analyses supported two clades: clade A and clade B. Members of clade A were found in Southeast Asia and northern Australia, but not in locations to the west (Gulf of Thailand) or north (China). Clade B was found exclusively in Southeast Asia. Genetic division along Wallace’s Line suggests that co-management of S. commerson populations for future sustainability may not be necessary between Southeast Asian nations and Australia, however all countries should share the task of management of the species in Southeast Asia equally. More detailed genetic studies of S. commerson populations in the region are warranted.

Healthy hardwoods. A field guide to pests, diseases and nutritional disorders in subtropical hardwoods.

Healthy hardwoods: A field guide to pests, diseases and nutritional disorders in subtropical hardwoods can be used to help identify the common damaging insects, fungi and nutritional disorders in young eucalypt (Eucalyptus and Corymbia species) plantations in subtropical eastern Australia. This guide includes photographs of each insect, fungus and nutritional disorder and the damage they cause, along with a brief description to aid identification. A brief host list for insects and fungi, including susceptibility and occurrence, is provided as a guide only. A hand lens will be useful, especially to identify fungi. Although it is possible to identify insects and fungi from these photographs, laboratory examination will sometimes be necessary. For example, microscopes and culturing media might be used to identify fungi. Information about four exotic pests and diseases has also been included in the Biosecurity threats chapter. Potentially, these would have a severe impact on plantation and natural forests if introduced into Australia. To prevent establishment of these pests, early detection and identification is crucial. If an exotic insect or disease is suspected, then an immediate response is required. Usually, the first response will be to contact the nearest Australian Quarantine and Inspection Service office or forestry agency to seek advice.

Healthy plantations. A field guide to pests and pathogens of Acacia, Eucalyptus and Pinus in Vietnam.

This book is a resource for those involved ‘on-the-ground’ with growing plantation trees in Vietnam, identifying the pests and diseases found on them, and managing the impacts of these organisms. The book, supported by AusAID’s Vietnam CARD (Cooperation for Agricultural and Rural Development) Program, and draws on the collective, long-standing experience of forest health scientists in Vietnam, Australia and South Africa. The book provides illustrations and information on 23 pests and 25 diseases of Acacia, Eucalyptus and Pinus for Vietnam; four of these species are important biosecurity threats not yet present in Vietnam.

CRC Field Analysis

Provide diagnostic support for plant pathology projects, including the maintenance and preservation of reference specimens.

Pests and Diseases in Field Crops

Insect pest diagnostics.

The first five days: field and laboratory investigations during the early stages of the equine influenza outbreak in Australia, 2007.

Until August 2007, Australia was one of only three countries internationally recognised to be free of equine influenza (EI). This report documents the diagnosis of the first cases of EI in Australian horses and summarises the investigations that took place over the next 5 days. During that time, a multifocal outbreak was identified across eastern New South Wales and south-eastern Queensland. The use of an influenza type A pan-reactive real-time reverse transcription polymerase chain reaction allowed rapid confirmation of suspect cases of EI.

A multi-field bio-economic model of irrigated grain-cotton farming systems.

We present a participatory modelling framework that integrates information from interviews and discussions with farmers and consultants, with dynamic bio-economic models to answer complex questions on the allocation of limited resources at the farm business level. Interviews and discussions with farmers were used to: describe the farm business; identify relevant research questions; identify potential solutions; and discuss and learn from the whole-farm simulations. The simulations are done using a whole-farm, multi-field configuration of APSIM (APSFarm). APSFarm results were validated against farmers' experience. Once the model was accepted by the participating farmers as a fair representation of their farm business, the model was used to explore changes in the tactical or strategic management of the farm and results were then discussed to identify feasible options for improvement. Here we describe the modelling framework and present an example of the application of integrative whole farm system tools to answer relevant questions from an irrigated farm business case study near Dalby (151.27E - 27.17S), Queensland, Australia. Results indicated that even though cotton crops generates more farm income per hectare a more diversified rotation with less cotton would be relatively more profitable, with no increase in risk, as a more cotton dominated traditional rotation. Results are discussed in terms of the benefits and constraints from developing and applying more integrative approaches to represent farm businesses and their management in participatory research projects with the aim of designing more profitable and sustainable irrigated farming systems.

Sensory Systems in Sawfishes. 2. The Lateral Line.

The lateral line system allows elasmobranchs to detect hydrodynamic movements in their close surroundings. We examined the distribution of pit organs and lateral line canals in 4 species of sawfish (Anoxypristis cuspidata, Pristis microdon, P. clavata and P. zijsron). Pit organs could only be located in A. cuspidata, which possesses elongated pits that are lined by dermal denticles. In all 4 pristid species, the lateral line canals are well developed and were separated into regions of pored and non-pored canals. In all species the tubules that extend from pored canals form extensive networks. In A. cuspidata, P. microdon and P. clavata, the lateral line canals on both the dorsal and ventral surfaces of the rostrum possess extensively branched and pored tubules. Based on this morphological observation, we hypothesized that these 3 species do not use their rostrum to search in the substrate for prey as previously assumed. Other batoids that possess lateral line canals adapted to perceive stimuli produced by infaunal prey possess non-pored lateral line canals, which also prevent the intrusion of substrate particles. However, this hypothesis remains to be tested behaviourally in pristids. Lateral line canals located between the mouth and the nostrils are non-pored in all 4 species of sawfish. Thus this region is hypothesized to perceive stimuli caused by direct contact with prey before ingestion. Lateral line canals that contain neuromasts are longest in P. microdon, but canals containing neuromasts along the rostrum are longest in A. cuspidata.

Spot Form of Net Blotch Resistance in a Diverse Set of Barley Lines in Australia and Canada.

The responses of 95 barley lines and cultivars to spot form of net blotch (SFNB) caused by Pyrenophora teres f. maculata were analyzed as seedlings and adults in Australia and Canada. Cluster analyses revealed complex reaction responses. Only 2 lines (Esperance Orge 289 and TR3189) were resistant to all isolates at the seedling stage, whereas 15 lines and cultivars (81-82/033, Arimont, BYDV-018, CBSS97M00855T-B2-M1-Y1-M2-Y-1M-0Y, C19776, Keel, Sloop, Torrens, TR326, VB0111, Yarra, VB0229, WI-2477, WI2553, and Wisconsin Pedigree) were resistant toward the two Canadian isolates and mixture of Australian isolates at the adult stages. In Australian field experiments, the effectiveness of SFNB resistance in three barley cultivars (Barque. Cowabbie, and Schooner) and one breeding line (VB9104) with a different source of resistance was tested. Barque, which possessed a resistance gene that provided complete resistance to SFNB, was the most effective and showed no effect on grain yield or quality in the presence of inoculum. Generally, cultivars with seedling or adult resistance had less disease and better grain quality than the susceptible control. Dash, but they were not as effective as Barque. A preliminary differential set of 19 barley lines and cultivars for P teres I. maculata is proposed.

Water and thermal regimes for field pea in Australia and their implications for breeding.

There is a large gap between the refined approaches to characterise genotypes and the common use of location and season as a coarse surrogate for environmental characterisation of breeding trials. As a framework for breeding, the aim of this paper is quantifying the spatial and temporal patterns of thermal and water stress for field pea in Australia. We compiled a dataset for yield of the cv. Kaspa measured in 185 environments, and investigated the associations between yield and seasonal patterns of actual temperature and modelled water stress. Correlations between yield and temperature indicated two distinct stages. In the first stage, during crop establishment and canopy expansion before flowering, yield was positively associated with minimum temperature. Mean minimum temperature below similar to 7 degrees C suggests that crops were under suboptimal temperature for both canopy expansion and radiation-use efficiency during a significant part of this early growth period. In the second stage, during critical reproductive phases, grain yield was negatively associated with maximum temperature over 25 degrees C. Correlations between yield and modelled water supply/demand ratio showed a consistent pattern with three phases: no correlation at early stages of the growth cycle, a progressive increase in the association that peaked as the crop approached the flowering window, and a progressive decline at later reproductive stages. Using long-term weather records (1957-2010) and modelled water stress for 104 locations, we identified three major patterns of water deficit nation wide. Environment type 1 (ET1) represents the most favourable condition, with no stress during most of the pre-flowering phase and gradual development of mild stress after flowering. Type 2 is characterised by increasing water deficit between 400 degree-days before flowering and 200 degree-days after flowering and rainfall that relieves stress late in the season. Type 3 represents the more stressful condition with increasing water deficit between 400 degree-days before flowering and maturity. Across Australia, the frequency of occurrence was 24% for ET1, 32% for ET2 and 43% for ET3, highlighting the dominance of the most stressful condition. Actual yield averaged 2.2 t/ha for ET1, 1.9 t/ha for ET2 and 1.4 t/ha for ET3, and the frequency of each pattern varied substantially among locations. Shifting from a nominal (i.e. location and season) to a quantitative (i.e. stress type) characterisation of environments could help improving breeding efficiency of field pea in Australia.

Corymbia leaf oils, latitude, hybrids and herbivory: a test using common-garden field trials

Foliar oils, particularly monoterpenes, can influence the susceptibility of plants to herbivory. In plants, including eucalypts, monoterpenes are often associated with plant defence. A recent analysis revealed an increase in foliar oil content with increasing latitudinal endemism, and we tested this pattern using three eucalypt taxa comprising a latitudinal replacement cline. We also examined the relative concentrations of two monoterpenes (alpha-pinene and 1,8-cineole), for which meta-analyses also showed latitudinal variation, using hybrids of these three taxa with Corymbia torelliana. These, and pure C. torelliana, were then assessed in common-garden field plots for the abundance and distribution of herbivory by four distinct herbivore taxa. Differing feeding strategies among these herbivores allowed us to test hypotheses regarding heritability of susceptibility and relationships to alpha-pinene and 1,8-cineole. We found no support for an increase in foliar oil content with increasing latitude, nor did our analysis support predictions for consistent variation in alpha-pinene and 1,8-cineole contents with latitude. However, herbivore species showed differential responses to different taxa and monoterpene contents. For example, eriophyid mites, the most monophagous of our censused herbivores, avoided the pure species, but fed on hybrid taxa, supporting hypotheses on hybrid susceptibility. The most polyphagous herbivore (leaf blister sawfly Phylacteophaga froggatti) showed no evidence of response to plant secondary metabolites, while the distribution and abundance patterns of Paropsis atomaria showed some relationship to monoterpene yields.

Grain dormancy QTL identified in a doubled haploid barley population derived from two non-dormant parents

Grain dormancy provides protection against pre-harvest sprouting (PHS) in cereals. Composite interval mapping and association analyses were performed to identify quantitative trait loci (QTL) contributing grain dormancy in a doubled haploid (DH) barley population (ND24260 x Flagship) consisting of 321 lines genotyped with DArT markers. Harvest-ripe grain collected from three field experiments was germinated over a 7-day period to determine a weighted germination index for each line. DH lines displaying moderate to high levels of grain dormancy were identified; however, both parental lines were non-dormant and displayed rapid germination within the first two days of testing. Genetic analysis identified two QTL on chromosome 5H that were expressed consistently in each of the three environments. One QTL (donated by Flagship) was located close to the centromeric region of chromosome 5H (qSDFlag), accounting for up to 15% of the phenotypic variation. A second QTL with a larger effect (from ND24260) was detected on chromosome 5HL (qSDND), accounting for up to 35% of the phenotypic variation. qSDFlag and qSDND displayed an epistatic interaction and DH lines that had the highest levels of grain dormancy carried both genes. We demonstrate that qSDND in the ND24260 9 Flagship DH population is positioned proximal and independent to the well-characterised SD2 region that is associated with both high levels of dormancy and inferior malt quality. This indicates that it should be possible to develop cultivars that combine acceptable malting quality and adequate levels of grain dormancy for protection against PHS by utilizing these alternate QTL.

Mapping Quantitative Trait Loci for Partial Resistance to Powdery Mildew in an Australian Barley Population

Genomic regions influencing resistance to powdery mildew [Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal] were detected in a doubled haploid (DH) barley (Hordeum vulgare L.) population derived from a cross between the breeding line ND24260 and cultivar Flagship when evaluated across four field environments in Australia and Uruguay. Significant quantitative trait loci (OIL) for resistance to B. graminis were detected on six of the seven chromosomes (1H, 2H, 3H, 4H, 5H, and 7H). A QTL with large effect donated by ND24260 mapped to the short arm of chromosome 1H (1 HS) conferring near immunity to B. graminis in Australia but was ineffective in Uruguay. Three OIL donated by Flagship contributed partial resistance to B. graminis and were detected in at least two environments. These OIL were mapped to chromosomes 3H, 4H, and 5H (5HS) accounting for up to 18.6, 3.4, and 8.8% phenotypic variation, respectively. The 5HS QTL contributed partial resistance to B. graminis in all field environments in both Australia and Uruguay and aligned with the genomic region of Rph20, a gene conferring adult plant resistance (APR) to leaf rust (Puccinia hordei Otth), which is found in some cultivars having Vada' or 'Emir' in their parentage. Selection for favorable marker haplotypes within the 3H, 4H, and 5H QTL regions can be performed even in the presence of single (major) gene resistance. Pyramiding such QTL may provide an effective and potentially durable form of resistance to B. graminis.